PD-L1 expression and survival in patients with non-small cell lung cancer (NSCLC) in Korea.

8066 Background: Data are limited on whether programmed cell death ligand-1 (PD-L1) expression is a prognostic factor among patients (pts) with NSCLC. Methods: We evaluated the relationship between PD-L1 expression and overall survival (OS) in 779 NSCLC pts treated at Samsung Medical Center, Seoul, Korea, between 2001 and 2010. Tumor expression of PD-L1 was measured by immunohistochemistry, and PD-L1-positivity was defined as staining in ≥1% of cells. Kaplan-Meier methods, log-rank test, and Cox proportional hazards models were used for survival analysis, adjusting for age, gender, smoking, and stage. Results: Median pt age was 64 years (range, 21-86 years), and 74% of pts were male. 49% of pts had adenocarcinoma, 39% squamous cell carcinoma (SCC), and 12% large cell carcinoma or other. Disease stage was I/II in 71% and III/IV in 29%. All pts underwent surgery, and 411 pts received chemotherapy. Median follow-up time was 4.2 years. Overall, 50% of pts were PD-L1-positive. A statistically significant highe...